1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to digital broadcast reception, and more particularly, to outputting video frames while changing channels using a digital broadcast receiver, in which channel-changing latency that may occur when changing channels using a digital broadcast receiver can be reduced.
2. Description of the Related Art
Digital broadcast receivers restore digital data from broadcast signals which are transmitted thereto using a digital transmission method. Digital broadcast transmitters such as broadcasting stations (hereinafter referred to as “head-ends”) convert analog signals into digital signals having logic values of 0 and 1, compress the digital signals along with additional information, and transmit the compressed digital signals using a digital transmission method. Then, digital broadcast receivers restore original video and audio signals from compressed digital signals transmitted by digital broadcast transmitters.
Digital technology is more robust against noise, consumes less power, and results in less degradation of data-regardless of transmission, copy, and accumulation operations than analog technology. In addition, digital technology, unlike analog technology, can employ an error-concealment technique. Moreover, digital technology contributes the compression of wideband video and audio signals, and the facilitation of data searches, data processing, and data-editing operations. Thus, digital broadcasting can provide various advantages over analog broadcasting by realizing robust, highly-efficient data transmission methods.
Digital broadcasting has enabled the delivery of audio/video data to the homes of viewers with little or no data loss. Also, digital broadcasting has enabled the transmission of various additional information, and has thus enabled viewers to enjoy various broadcast content. For example, it is possible to enhance the viewing experience when the viewer watches, for example, a sports game, by providing the viewer with information regarding players of the sports game in real time.
However, the speed of changing channels using a digital broadcast receiver is much lower than the speed of changing channels with an analog broadcast receiver. In the case of analog broadcasting, a channel corresponds to a broadcasting station, and, thus, a broadcast station can be identified by a corresponding channel number. In contrast, in the case of digital broadcasting, a channel corresponds to a broadcast program, i.e., an audio/video stream or an additional data service stream, and, thus, a channel number denotes a program identifier (PID).
Changing digital broadcast channels is generally carried out by searching for a PID of a channel that a user wishes to tune to. Since PIDs continuously vary according to the circumstances of broadcasting stations or broadcast programs, and the search of PIDs often results in latency, the speed of changing digital broadcast channels is generally lower than the speed of changing analog broadcast channels.
In order to address this, a method which involves receiving a plurality of transport streams (TSs) from respective corresponding channels using a plurality of tuners has been suggested, decoding one of the TSs originating from a channel to be displayed as a packetized elementary stream (PES), dividing the PES into a video elementary stream (ES) and an audio ES, and decoding the video ES and the audio ES separately, and outputting the decoded video ES and the decoded audio ES has been suggested. According to this conventional method, a TS of a channel adjacent to the channel to be displayed is decoded as a PES, but is not output. When a user changes the channel to a channel adjacent to the channel to be displayed, a PES of the adjacent channel is divided into a video ES and an audio ES, the video ES and the audio ES are decoded separately, and the decoded video ES and the decoded video ES are output.
This conventional method, however, requires the installation of as many tuners as there are TSs. If there are fewer tuners than TSs, a PES discontinuity may occur. If a decoding operation is performed when a PES discontinuity is present, a frame error or degradation may occur.
Also, the conventional method only takes into consideration changing the channel to either a channel directly above or below a channel currently being watched by a user, and thus may not be able to appropriately respond to various user demands regarding changing channels.